Comparing two recurrent selection methods for developing superior apomictic hybrids in Paspalum notatum

Abstract

Recurrent selection methods have been successful in generating superior Paspalum notatum families through the accumulation of favorable alleles. However, the effectiveness of these methods in producing apomictic hybrids with superior agronomic traits has not been thoroughly evaluated. The aim of this study was to characterize the reproductive behavior of P. notatum progenies obtained through recurrent selection based on combining ability (RSCA) and recurrent phenotypic selection (RPS) and assess the performance of the apomictic hybrids concerning various agronomic traits. The reproductive mode of 144 RSCA and 144 RPS hybrids was determined using a molecular marker tightly linked to the apospory trait (BCU243-377). The expressivity of apospory was estimated observing mature embryo sacs. The apomictic hybrids were then evaluated for six agronomic traits. A segregation ratio of 5:1 between sexual and apomictic hybrids was observed for the RSCA progeny, while 4.3:1 was registered for the RPS progeny. Although apospory expressivity was variable among hybrids, 75% and 86% of the RSCA and RPS hybrids, respectively, exhibited a high expression (>81%). Non-significant differences between breeding methods in the number of apomictic hybrids and the level of apospory expressivity were observed. Variations for all agronomic traits were observed among apomictic hybrids within each breeding method. However, no differences between methods in the performance of the highly apomictic hybrids were observed. This demonstrates the reproductive behavior of P. notatum is not affected by the recurrent selection method. Therefore, the RPS method would be the most suitable since it was equally effective than RSCA but it is cheaper, faster, and easier to apply.